Insulating filament



i synthetic r medoce a, 1929' NI ED STATES PATENT OFFICE I my A. GARDNER, or

hrsmrme Ho Drawing.

The present invention relates to artificial filam'ents and resides more particularly. in artificial filaments consisting essentially of a cellulosicmaterial and containing an added insulating material.

It is known that pure silk filaments possess a considerable degree of electrical resistance and hence find applicability in the electrical industryin the preparation of non-conducts ing coverings for conductor wires such, for

instance, as the wires used in the telephone instrument. It has been demonstrated that the known artificial filaments such as artificial silk generally are not as satisfactory as pure silk for electrical insulating purposes.

An object of the present invention, therefore, is to provide a. relatively non-conduct ing artificial filament having improved prop erties .in this respect. V V

.I have found that it is possible to prepare artificial filaments, such as, for example, artificial silk, having insulating or.non-conducting properties equal or superior to those possessed by natural silk, by ,commingling with the solution of cellulosic which the filaments are to be formed a mate rial known tobe a relatively good non-co'n ductor, extruding the resulting composition through capillaries and further processing the so-formed-filamentsin the known manner. 1 I have found that the non-conducting material becomes apart of the filament, giving to it a relatively. high degree of electrical resistance and other desirable properties with the result that the new filament may be a n0n-conductor as good as, if not better than, natural silk.

The cellulosic filament-forming constituent of the extrudable'composition may be a 40 solution of cellulose acetate, cellulose nitrate,

acetyl-nitro-cellulose, viscose, cupro-ammonium cellulose, or in general any of the known filament-forming esters or ethers of cellulose, or regenerated cellulose. thej'-non-conducting material to be incorporated in the filaments there may be used any of the materials known to posses relatively highwelectrical resistance, including mica and other non-conducting materials,

resins. Among the natural resinsmaterial from :shell and natural tr wasnmeron, nrsrarcrr orconumam I'HiAMENT,

Application filed January 10, 1928. Serial No. 245,812.

suitable for this purpose are shellac,dammar, rosin esters and the like. Some of the suitable synthetic resins are: phenol-foririaldehyde condensation products, glycerinphthalic acid condensation-products, urea- 1fiirmaldehyde condensation products and the The following will serve to illustrate the invention, it being understood that the in vention is not limited to the precise starting materials mentioned nor to the relative pro portion of non-conducting component to filabe required by the claims:

Example 1.About 40 grams of a resin solution, containing approximately 20 grams of phenol formaldehyde synthetic resin, are incorporated by thorough mixing into an acetone solution of 100 grams of cellulose acetate. The resulting composition is projected through capillary orifices, and the resulting aments,-a;fter coagulation,are and further processed in the terms of the appended OYVII 1113111181.

resin of the above example I may substitute a natural resin such as for example shellac, or another synthetic resin; or, I may replace a part of the synthetic resin content by an equivalent of-a natural resin.

Example 2.-About 10 grams, more or less, of finely divided mica are thoroughly milled with 20 grams of an acetone solution of a resin containing approximately 5"gr'ams of phenol-formaldehyde resin and 5 grams of ac. After thorough milling, the result- 111g mixing, into an acetone solution of100 grams o f 'cel lulose acetate. The resulting composltion is projected through capillarly orifices,either into the air or, if desired, into a suitable coagulating medium,-and the resulting extruded filaments are dried and further procissed in the manner known to 4 the artificial silk art.

I claim: e 1. Asa new article of manufacture, a cellu: losic artificial filament containing an elecically non-conductingmsinand a finelydivided non-conducting'niicaceous substance in For the phenol-formaldehyde synthetic 'mcnt 'forming component, excepting as may dried 7 suspension is incorporated, by thorough 2 I 1,730,417 amounts suificientfito produce-an electrically ect.

non-conducting e 2. As a new art1cle of manufacture, a cellulosic artificial filament containing an electric'ally non-conducting synthetic resin and finely divided mica in amounts suflicient to produce anelectrically non-conducting effect. 3. As a new article of manufacture, a cellulosic artificial filament containing an electrically non-conducting synthetic resin, shellac, and finely divided mica in amounts suf-' ficient to produce an electrically non-conducting efiect.

In testimony whereof, I

' HENRY afiix my signature. A. GARDNER. 

